Due to current technology trends, television is becoming an increasingly interactive medium. Currently, more that 20 million users subscribe to interactive television services in the United States alone. Interactive television combines traditional television viewing with the interactivity of the Internet and the personal computer. End users can enjoy customized programming content, links to Web sites through television links, electronic mail, chat room activity, and online commerce using their television by communicating information and requests back to the service provider using a back channel.
Some of the features of interactive television programming include interacting with television shows (e.g., game shows, news polls, and surveys), interactive entertainment and programming guides, video conferencing, interactive gaming, distance learning, instant messaging and e-mail. A variety of commercial transactions can also be supported such as home banking and home shopping.
Service providers (e.g., cable companies, satellite television operators etc.) are also focusing upon creating fast content delivery networks capable of delivering high bandwidth (e.g., 550 MHz to 1 GHz) television broadcasts to end users. The increased bandwidth facilitates providing users with a wider variety of programming and services. Additionally, as the emerging Digital Television standards gain acceptance, the interactive features offered to end users will be increased because digital televisions systems are capable of using the available bandwidth more efficiently.
However, while television technology is becoming increasingly sophisticated, the means of interacting with it are not. The most common method for a user to interact with a television comprises entering key presses to indicate which channel the end user wants to view. Alternatively, the end user can control a simplified menu interface by using directional buttons to highlight a desired menu selection. Many users find this system inconvenient and time consuming and would prefer a control interface that looks and functions in a manner similar to a web browser interface, with which many of the users are already familiar. However, the directional buttons used with prior art television control devices are not well suited for controlling the movement of a cursor.
For example, web pages are designed with the idea that the user is controlling an on-screen pointer (e.g., arrow pointer or cursor) by moving a mouse. Efforts have been made to adapt this method to television interfaces by adding a mouse or a trackball device as a second input device to the television. This is inconvenient for many users because the user has to switch between different input devices to interact with the television. Placing a trackball on the remote controller itself eliminates the need for a dedicated cursor controller, but is difficult for many users to operate as well.
U.S. Pat. No. 5,440,326; titled “Gyroscopic Pointer,” issued Jan. 5, 1993, and U.S. Pat. No. 5,825,350; titled “Electronic Pointing Apparatus and Method,” issued Oct. 20, 1998, as well as U.S. Pat. No. 5,898,421; titled Gyroscopic Pointer and Method,” issued Apr. 27, 1999, describe pointing devices which are used to control the movement of a cursor. These devices determine how much the controller has been moved using mechanical gyroscopes and use this information to re-position a cursor a comparable distance upon a computer display.
Mechanical gyroscopes calculate the angle a device has moved due to changes in the rotational velocity of the gyroscope. However, mechanical gyroscopes are subject to a phenomenon called bias drift which results in significant margins of error over time. For example, a stationary gyroscope should output readings showing no change in rotational velocity. In reality, the readings will differ from that ideal value due to bias drift. Each calculation of angle introduces a margin of error, and as the angles are added together, this margin of error becomes greater and greater and can, over time, make it practically impossible to accurately determine angular displacement.
Another controller is taught in U.S. Pat. No. 4,862,152 titled “Sonic Positioning Device,” issued Jan. 25, 1990. This device senses the position of a controller in three dimensions by sensing the position of an ultrasonic transmitter relative to an array of ultrasonic receivers. However, this device does not determine a point on a display device at which the controller is pointed, but relies upon being able to sense the position of the controller itself. Because the controller must be repositioned rather than simply reoriented, relatively large hand movements are required to define cursor movements. Additionally, this controller relies upon ranging techniques, the range and resolution of the device is limited.